Sparkless electric &#34;toggle&#34; switch



Dec. 20, 1955 R R PROCTOR 2,727,959

SPARKLESS ELECTRIC "TOGGLE" SWITCH Filed Deo. 26, 1952 2 Sheets-Sheet 1 FIG. l

IN VEN TOR.

BY f90/VALL? PROOTO? TTORNE Dec. 20, 1955 R. R. PRocToR SPARKLESS ELECTRIC "ToGGLE SWITCH 2 Sheets-Sheet 2 Filed Dec. 26, 1952 IN VEN TOR.

BY RONALD PROGTOR ATTORNEY United States Patent O SPARKLESS ELECTRIC TOGGLE SWITCH Ronald R. Proctor, Crystal Lake, Ill., assigner to 'lhe Pure Oil Company, Chicago, Ill., a corporation of h10 Application December 26, 1952, Serial No. 327,995

3 Claims. (Cl. 200--112) The present invention relates to mercury switches designed to carry heavy currents without sparking, and, more particularly, the invention relates to a combination lever and magnetic arrangement for actuating a mercury switch.

Many dilerent types of sealed mercury switches employing a mercury-to-mercury contact for making and breaking the circuit are known. The advantage of this type of switch is that erosion of terminals is eliminated, open sparking is avoided, and the making or breaking of the circuit is positive and generally instantaneous. An incidental advantage is that the operation is essentially silent. Mercury switches of this type, sometimes known as mercury relays, generally comprise a hollow, sealed, cylindrical body of glass,'plastic, or stainless steel containing mercury and a gaseous atmosphere of nitrogen or hydrogen above the mercury. A core element comprising a paramagnetic core surrounding a cup-shaped insulating body lloats in the mercury. The insulating body is generally in the form of an elongated cup, open at its top, with the paramagnetic core located around the lower or bottom end. The top inner cup portion of the insulating body is lled with mercury on submerging therein and this mercury is in constant contact with one terminal of the switch which is sealed through the wall of the hollow body. The other terminal, which also may be sealed through the wall of the hollow body or many comprise the body of the core element, is in contact with the mercury surrounding the insulating body and core. Outside of the hollow body and adjacent thereto is a xed electromagnet which, on being energized, plunges the loating core and insulating body into the mercury whereby the mercury overflows the insulating top portion and spills into the cup, thereby closing the circuit. Deenergization of the electromagnet allows the core and insulating body to rise and break the circuit. Mercury switches -of the plunging core type are described in United States Patents 1,935,710 and 1,861,630 by Charles Hatay, and 1,786,018 by i. E. McCabe. Switches of this type employ an external electromagnet which must be energized and deenergized by a separate current supply in order to operate the switch. This means the use of either another switch arrangement with the consequent danger of sparking or an electronic relay of some sort which increases the bulk and expense of a mercury switch installation.

ln United States Patent 2,101,092 by J. H. Payne, Ir., there is described a mercury switch which is mechanically actuated. Payne`s switch comprises two dished or concave metal members assembled in juxtaposition with an apertured disc of suitable refractory material held therebetween. The concave members with the insulating apertured disc when assembled form a Hat-ended spherical body or cell with the disc dividing the interior in half. Mercury is provided in the interior of the cell and each half of the cell is a terminal of the switch. In one form of Paynes switch, it is rotated about an axis running perpendicular to the disc, thereby allowing mercury-to-mercury contact when the ofi-center aperture rotates into 2,727,959 Patented Dec. 20, 1955 the mercury. In another form of Paynes switch, the aperture is rather large and centered in the insulating disc. Making and breaking of the circuit is accomplished by tilting the spherical body in about a 45 arc on an axis running coincident with the plane of the disc, thereby causing mercury to spill over the periphery of the large aperture. For both the rotating and tilting action of this switch the cell must be supported by a pair of spring clips which are connected to electrical terminals. The spring clips have their surface of contact shaped to tit the outer surface of the concave metal members and serve as a bearing and supporting means. In actual operation, dust and dirt accumulate between these clips and the metal members and cause heating and consequent loss of spring tension, thereby causing sparking when the switch is operated. Consequently, such switches are not adapted for use in hazardous atmospheres where a minute spark may set off an explosion.

In addition, to make this switch small enough to t in standardized (nationally among all manufacturers) switch boxes, the cell is small and the small cross-section of mercury available to make and break the contact, as well as the small amount of gas permissible to quench the arc, limits the rating or current-carrying capacity of such switches. (5 and 10 ampere ratings are standard. The switch of the present invention may carry currents up to 30 amperes.)

The disadvantages of the prior art mercury switches are overcome by the present invention whereby a lever arrangement is employed to move a permanent magnet and thereby actuate a plunging core mercury switch without the danger of sparking. In mercury switches of my invention, a plunging core mercury switch of the type described by Hatay and McCabe, aforementioned, may be employed. The mercury switch is mounted in an iusulated housing fitted with suitable mounting ears. The body of the mercury switch is in space relationship with a permanent magnet which is raised or lowered to attract and move the floating core. The body of the mercury switch is preferably cylindrical and fits between the poles of the permanent magnet. By this construction, there is provided a direct means of operation without the danger of sparking and the switch is adapted to installation in ordinary wall outlets or in switch boxes for use with heavy current loads necessary in industry.

It is a fundamental object of this invention to provide a manually-operated sparkless mercury switch for use 1n hazardous atmospheres.

h lt is a second object of this invention to provide a particular operating mechanism for plunging core type Inercury switches.

Still another object of this invention is the provision of a magnetic means for actuating the plunging core of a mercury switch in a manner that is free from sparking.

Still another object is to provide a high-capacity, silent, sparkless switch which will tt into standard switch boxes.

The present invention is best described by reference to the drawings which form a part of this specification:

Figure 1 is a cross-sectional view along lines A-A of the switch housing to show the mercury cell and lever arrangement wherein the bottom portion of the cell has been cut away to enable the showing of the floating core.

Figure 2 is a back sectional view along lines B B of the switch showing the housing in cross-section and a cutaway view of the top portion of the mercury cell to expose its functional parts in cross-section.

Figure 3 is a top sectional-view taken along lines C C of Figure 1 with the lever-handle in horizontal position.

Figure 4 is a front view of the switch.

Figure 5 is a perspective view of one form of magnetic means showing the inner insulating liner in place.

Figure 6k is a perspective view of one form of leverhandle.

Referring to the drawings, the housing 2 is substantially rectangular in shape and adapted` to be inserted into wall openings or switch boxes and mounted thereto by means of strap 4 with mounting ears 6 and 8.v Cover plate lil, made of insulating material, tits over the front of the housing 2 and is held in place withY strap 4 by screws 12 and 14. Screw i4 is shown as threaded into boss lr6 and screw l2 aflixed through housing 2 by means of nut 18. Cover plate l@ and strap 4 are provided with coincident apertures at 2@ through which the lever-handle 22 protrudes. The plunging core mercury cell is represented at 24 and is of the type previously described. Cell 24 is connected by means of terminal wires 26 and 28 to terminal screws 3@ and 32 md angle-plates 34 and 36 for easy connection of the cell therein and of the switch into a circuit. Leverhandle 22 is pinioned through hole 38 on shaft 4t), which may be iournaled in shoulders 42 and 44 extending from and as part of cover l@ to the inside of switch housing 2. Shaft 40 may be held in position by any appropriate means as threaded fasteners 46 and 48 to facilitate removal of the lever-handle. A. spring-loaded detent 50 is located in shoulder 42 and is adapted to impinge upon depressions 52 and 54 within lever-handle 22 to hold same in on and off positions, respectively. Lever-handle 22 has two yoke arms Se and 58 with slots 6G and 62, which engage pinions 64 and 6d in collar 68. Collar 68 encompasses cell 24 and is adapted to be slidably moved up and down by the movement of lever-handle 22 and the sliding engagement of slots 6d and 62 on pinions d4 and 66. Collar 63 has an axial bore slightly larger than the outside diameter of cell 24 and may be insulated therefrom. Linkages 7d and 72 engage pinions 74 and 76 on collar 68 and carry the magnet 7S through pinions 84) and 82, engaging holes, like 84, in the side of the magnet 7S. Magnet 78 has an axial bore 86 between its poles slightly larger than the outside diameter of cell 24 and may be insulated therefrom as indicated by cylindrical insulator 88. One form of magnet 7S is shown in Figure 5. This arrangement allows for the movement of magnet 7 3 in a substantially vertical path by the movement of lever-handle 22 up and down, thereby engaging spring-loaded detent Sil back and forth from depressions 52 and 54, i. e., from off to on position. In embodiments shown, not only is the movement of the magnet 78 in a substantially vertical path made possible, but the switch is adapted to easy and quick assembly since rst the collar linkage and magnet unit may be inserted over the cell and the latter iixed within the housing, then the lever-handle is inserted in the shoulders of the cover plate, the mounting strap is aligned therewith, and the assembly is then lixed to the housing while the slots of yoke arms engage the pinions of the collar. In fabricating the linkage arrangement, riveted pins may be used for pinions shown.

The plunging core, adapted to make and break mercuryto-mercury contact within the cell, is generally indicated by 9G and shown in normal floating position within mercury body 32 in Figure l. This core comprises a ceramic cup 94 fitted with paramagnetic or iron core 96. The weight relationship and shape of these parts are adjusted so that when the plunging core 9d is in floating position (oti` position), the upper periphery or rim of the ceramic cup 94 cuts or separates the surface of the mercury body 92. A portion of the mercury is within the inside of cup 94 and in constant Contact with one terminal, 98, of the switch, to be described. Terminal 98 fits within cup 94 as shown and its lower end acts as a stop for the upward movement of the cup and core as it is buoyed by the mercury. In the construction shown, housing of cell 24 is made'up of non-magnetic conducting material which will not amalgamate or alloy with mercury (preferably an 18-8 stainless steel), and acts as the second terminal of the cell. insulator u separates terminal 90 from the conducting wall of cell 24. Thus, movement of leverhandle 22 upward to on position causes magnet 78 to attract iron core 96 and pull the plunging core 90 into the mercury 92, whereupon mercury ows over the top rim of cup 94 and completes the circuit between the body of the cell 24 and terminal 98. Detent 50 impinges in depression 54 to hold the lever 22 in place. Flicking the switch to olf position as in Figure l allows the core 90 to rise under the buoyant action of the mercury, plus the attraction of the magnet 78, and the rim of cup 94 breaks the mercury-to-mercury contact. Detent 50 impinges in depression 52 to hold the switch in position.

The switch housing 2, lever-handle 22, and insulators 83 and lll() may be of any non-conducting material, as, for example, plastic, hard rubber, resinous materials, laminated resinous materials, or the like. Strap 4 is preferably constructed of metal to insure rigid fastening of the switch to the wall or other means of support.

Any form of permanent magnet may be used as long as it retains its magnetic property over extended periods of time.v Many metal and metal alloy combinations are now available which have this property of permanent magnetism. Alloys of nickel, chromium, and molybdenum with iron form very long-lived magnets. Alloys of cobalt and platinum are extremely strong magnetic materials but prohibitive in cost. The proprietary products manufactured under the trade names Permalloy, Carboloy, Perminvar, Armco, Alnico, and Alnico-S are very suitable magnetic materials to be used.

In a magnet of the form shown in Figure 5, the strongest field is across and through the axial bore in the iniddle of the magnet between the poles. Magnets used in accordance with this yinvention may be designed to concentrate their magnetic fields in the center of the axial bore for most eicient attraction of paramagnetic core 96.

Referring to Figure 6,v further detail of the lever-handle is shown with depressions S2 and 54 in full view. This lever-handle may be moulded in one piece of suitable plastic material.

Other details of construction include screws T192, M4, 106, and 1.68, which are recessed in holes, like llt), to engage angle-plates 34 and 36 in the manner shown. A similar recess 112 is shown for screw l2. After assembly, these recesses are iilled with molten tar or other nonconducting material, adapted to harden and seal the recesses and insulate the metallic parts therein.

Asshown in Figure 4, cover plate lll is offset at its upper corners to expose terminal screws rtl4 and 116 to offer easily accessible means of connecting the switch into au electrical circuit. Shoulders 40 and 42 protruding inwardly from cover plate l0 to support lever-handle 22 may be constructed as part of strap 4, in which arrangement (not shown) they would be so shaped as to pass within the opening 20 of cover plate lil'. Deteut 5l) in this instance would be held within a flat, flared rivet pressed within a hole in one of said shoulders.

The four pinions 64, 66, 74, and 76 of collar 63 are spaced diametrically opposite from one another at 90 intervals around the collar. This construction balances the weight of the linkages and 72 and the magnet 73 thereon. As previously pointed out, both collar 68 and magnet I8 `encompass the outside of cell 24 in sliding relationship with only their insulated inside surfaces, as illustrated by insulator 8S, a duplicate of which may be within collar 68, passing in space relationship with the cell 24. This construction insures against any accidental sparking or static discharge during operation of the switch. insulator 88 may be attached to the outside or' cell 24 instead of to magnet 73 as shown and extend over the entire outer surface thereof which is adjacent the magnet and collar during their normal up and down travel.

Strap 4 is embedded within a recess within the outer surface of cover plate lil (Figure l), such recess being shaped to conform with the outer contour of strap 4 as shown in Figure 4, to provide added rigidity.

Although the invention has been described by refer ence to particular embodiments thereof, it is to be understood that various changes, omissions, and substitutions within the scope of the appended claims, may be made therein without detracting from the spirit of the invention. Although one magnet has been shown, two or more magnets may be used in such manner as to exert a magnetic field to attract said plunging core by juxtapositioned opposite poles.

What is claimed is:

l. A mercury switch adapted to be used in vertical position comprising an insulated housing with internally extending bosses, a plunging core mercury cell within said housing, said mercury cell comprising a conductor housing, a body of mercury in said conductor housing, a paramagnetic core oating on said body of mercury, a ceramic cup on said core, said ceramic cup having a continuous horizontal rim, another body of mercury in said cup, an electrode extending into said second body of mercury, said bodies of mercury merging and separating on said rim on vertical movement of said core, lever means pivotally mounted between said bosses, a yoke at one end of said lever, a collar pivotally mounted within said yoke, said collar encompassing said conductor housing and adapted to reciprocate thereon, linkage means attached to said collar, a permanent magnet attached to said linkage means, said magnet having its poles on opposite sides of said conductor housing of said cell and adapted to reciprocate thereon, insulator means between said magnet and said collar and said conductor housing, said magnet being opposite said paramagnetic core and adapted to impart vertical movement to said core on movement of said magnet by said linkage and lever means.

2. A sparkless mercury switch comprising in combination an insulated housing, opposed spaced inwardly extending shoulders on an inner wall of said housing, an opening in said wall between said shoulders, a plunging core mercury cell fixed within said housing, said cell adapted to make and break mercury-to-mercury contact upon raising and lowering said plunging core, a leverhandle pivotally mounted between said shoulders and within said opening, a spring-loaded detent within one of said shoulders, said detent impinging against said lever-handle to hold same in raised and lowered position, said lever-handle having opposed spaced inwardly extending yoke arms with open-ended slots in said arms, an annular collar encompassing and spaced from said cell, outwardly extending pinions circumferentially 1ocated about said collar equidistant from one another, a pair of said diametrically opposite pinions engaging said slots in said yoke arms, a second pair of said diametrically opposite pinions engaging the top ends of two linkage members, a permanent magnet pivotally supported between the bottom ends of said linkage members, said magnet comprising an elongated two-poled member with a transverse aperture between said poles, Said aperture encompassing and spaced from said cell at point below said collar whereby pivotal movement of said lever-handle raises and lowers said magnet and moves said core by magnetic attraction to make and break mercury-to-mercury contact in said cell.

3. A mercury switch comprising, in combination, an insulated housing, an operating lever pivotally mounted through one side of said housing, a stationary cell partially filled with mercury and a stationary contact mounted in the upper portion of said cell, a movable magnetic plunger immersed in said mercury, a magnet carrier member mounted for slidable movement along said cell, connecting means between said operating lever and said magnet carrier whereby said carrier is caused to slide along said cell upon operation of said lever, a permanent magnet attached to said magnet carrier member, said permanent magnet having transversely located poles and an aperture in said magnet between said poles to accommodate said cell, the movable magnetic plunger of said mercury switch being located in said cell between said poles whereby operation of said permanent magnet moves said magnetic plunger to displace said mercury into and out of contact with said stationary contact.

References Cited in the file of this patent UNITED STATES PATENTS 1,786,018 McCabe Dec. 23, 1930 2,401,767 Larson June ll, 1946 2,474,000 Keating June 21, 1949 2,520,935 Hubbell Sept. 5, 1950 FOREIGN PATENTS 485,564 Great Britain May 16, 1946 613,270 Great Britain Nov. 24, 1948 

